Base Bracket Design

AIM: Create the Base Bracket Plastic component through the given Class-A surface. To begin with, the tooling axis for the given Class-A Surface should be created meeting the draft angle requirements and performing the draft analysis on the model at the end.

INTRODUCTION

The Draft allows the part to easily eject from the mold. The draft angle is to reduce friction between the core, cavity, and part and it also avoids damage. The minimum draft angle is 0.5 degrees and the most common draft angle used in the plastic design is 3 degrees.

In CATIA the draft analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction at any point, corresponds to specified values.

Tooling direction is the main element to be considered while designing a plastic component. In the molding machine, the arrangement is given to open the mold in the direction. It is the direction in which the core and cavity open.

CLASS A SURFACE

1. Visible surface and aesthetic look
2. Surface with textures
3. Surfaces provided by customer(OEM)
4. Don't have any features like(rib, snap, bosses, etc.) on class A surface.
5. Class A surface is made from scanned data with different software like alias etc.
6. Surfaces which is having CURVATURE CONTINUITY are CALLED class-A.

CLASS B SURFACE

1. Invisible Surfaces.
2. Surfaces mostly don't have textures
3. Surface needs to be created according to class-A surface.
4. Having all features(Rib, boss, snap, etc.) on the B-side surface only.
5. Surfaces which is having TANGENT CONTINUITY IS CALLED class-B

CLASS C SURFACE

Which join both Class-A and Class-B Surface

PROCEDURE

• First the connectivity between the surfaces is to be checked, by using the join option to see how the surface is connected and ensure that there are no surface gaps in between the component.
• The other method to check connectivity is using the boundary option. By Extracting and disassembling the boundary of the class-A – Surface we can check visually gaps between the surface.
• Create a boundary for the hole in the Base bracket. Using Circle / Sphere / Ellipse centre option create a point w.r.t the boundary. Create a line using the point – the direction(z) option that line is a dummy tooling axis.
• Create a plane w.r.t point created before and YZ plane
• An intersection sketch is made using the YX plane and the class a surface
• By using the point–point line option extend the line along the sketch. With the bisecting line option selecting the two lines the TOOLING AXIS is created.

DRAFT ANALYSIS

• For plastic parts the Nominal draft angle is 3deg, but even 7deg is allowed for the subassemblies like ribs and slots
• INSERT - ANALYSIS - FEATURE DRAFT ANALYSIS
• First the compass is moved to the part (the compass should be placed on the tooling axis) which used to define the new current draft direction, then lock the draft direction using the lock icon
• The color chart indicates the various condition of the draft angle. the green color indicates that the part passes and the and can be used for the further operations
• By using the analysis under the running point icon we can check the draft angle at the various surfaces of the component
• There are two modes in the Draft analysis quick mode and fully detailed mode.

CREATING CLASS B SURFACE

• First work on the ribs. Extract the top surface of the first rib with No propagation and also extract both side surfaces of the ribs. Untrim the surfaces one by one and hide the extract
• Extrapolate all the untrimmed surfaces one by one (Click on the boundary and the surface)
• Now, Trim the first and the second surface, and Trim the Trim1 and the third surface
• Offset the surface to 2.5mm which is the thickness
• Repeat the steps for Rib 2, connecting the surface and the base surface
• Fillet the surface where ever required.

CREATING CLASS C SURFACE

• The boundary is created for the Class-A surface, and the boundary of both holes in the surface is also created.
• Sweep (Draft with direction) the boundaries one by one with tooling axis with 3Deg draft angle
• Use the join option to combine all the swept surfaces
• Trim the joined surface with the Class-B Surface to form the Class-C surface

PUBLICATIONS

• TOOLS - PUBLICATION
• Publication is done because It can be easily visible and can be easily accessible while performing further operations
• Select the Base bracket (Class A Surface) (Class-B&C) the tooling axis and select Publish

PART BODY

Convert the obtained Class-C surface into the part body using the Close surface option

CONCLUSION

From the given Class-A Surface, Class-B and Class-C Surface were created and tooling axis for manufacturing was created and draft analyses were carried out successfully.